post_proc: Enable reverb in DSP to start effect

During switch to tunnel playback, reverb enable command is not sent to
DSP and causes reverb effect not applied continuously.

Send reverb enable params to DSP to start effects during switch.

Change-Id: I6e8bbdf4c1e5933be9a37413a4c4f1b7106fe6ba
CRs-Fixed: 637016